@Detlef: A larger population is only necessary if there’s a crapload of work to be done right now. There isn’t, because I can guarantee you the first merchant who shows up doesn’t have very much money to pay his wood-choppers with. Once he starts making money, more unemployed locals will start chopping wood and bringing it to Mr. Merchant to sell. The colony would do best as simply a trading post and a safe harbor.
The locals know the paths around Vinland, while the Vikings know the sea route to Vinland. You can guess what people will do.
Historically, the Vinland colonists refused to sell iron weapons to the locals. The imports to Vinland would likely be food, animals, artisanal goods, and precious metals.
The original colonies were small: if they were prosperous, I doubt they would need large Viking populations. Likely a lot of mixed-race people in the second generation.
Vinland regardless would be seen as an outpost, a shithole at the edge of Viking influence, a bit like how Rome felt about England. I bet they would go to Iceland, as it’s closer to home.
Hmm, I´m not an expert for that time period so I may be totally wrong here?
Fishing would be good in Iceland but the farmland isn´t that good.
A TV documentary I saw some time ago mentioned serious problems with wind erosion. Apparently without ground "cover" (plants, trees whose roots "fix" the soil) the relatively thin layer of fertile soil will be blown away.
Such a thin layer might explain the "marginal" farmland mentioned in some articles. Too much grazing by farm animals might destroy the ground cover too leaving barren land behind (the TV documentary showed some areas where replanting efforts were going on). Not sure how large trees could become in such conditions?
Vinland would offer much better farmland, good fishing, abundant timber. If Vikings were willing to settle in Greenland why not go a bit further? Especially when a man or family could build a much more prosperous farm there than in Iceland or Greenland (or much of Scandinavia itself)?
I seem to remember that once the Vikings conquered some parts of the British isles, a second wave of settlers came? Attracted by the promise of a more prosperous future?
Why shouldn´t the same happen with Vinland?
Mind you, I´m not talking about thousands of new settlers at once.
Just a steady trickle over the years once the news reach Greenland / Iceland / Scandinavia. Some years maybe only some 3th sons traveling on the trade ships to Iceland -> Greenland -> Vinland. In other years maybe some families with their own ship(s).
And staying closer to home?
Sure, in Iceland they might hear more general news about Scandinavia. But a family would be lucky if a traveler / trader might have some news about their families / region from back "home".
Per the TL we already got close to 2000 Viking males and several hundred females in Vinland (3 settlements). More females are definitely needed.
Farmers, fishers, hunters and wood-cutters. Plus some "explorers".
Given the numbers I also expect some blacksmiths, carpenters and shipbuilders soon starting their specialized trade. Plus of course merchants trading with Greenland and maybe Iceland.
Vinland could export timber, pelts, animal skins and dried or salted cod. Once they get more farms going they could even export some grain.
Imports would be farm animals initially (cows, pigs, sheep mainly. Maybe chicken, geese, ducks?) until they got enough to be self sustaining. Hopefully some ponies / horses from Iceland? And of course metals (iron, copper and the like) for now. Until they discover ore deposits in Vinland.
In case of food they already produce grain, they have fishing and hunting. Once they got their farm animals (milk, cheese) they only need some vegetables and fruit to have a pretty balanced diet. Some seeds / seedlings (cabbage, apple trees and the like)?
Oh, and flax seeds / seedlings (linen, linseed oil)l?
Or if the "Three Sisters" (maize, beans, squash) already exist in North America, they might stumble across it?
Pottery for now might be an import too.